Co-additive compositions and methods for applying co-additive compositions into nucleated polymer compounds

ABSTRACT

It is possible to improve significantly the optical performance of diacetal or DBS-based nucleating or clarifying agents using a co-additive. Haze is a measure of the lack of clarity in a thermoplastic or plastic material. A low level of haze is usually quite desirable, and nucleating/clarifying agents are designed to reduce the degree of haze in a plastic or thermoplastic material. A co-additive may be used in connection with a nucleating/clarifying agents in a polymer or copolymer to achieve even greater results in terms of improved clarity (reduced haze), or in terms of a higher crystallization temperature (Tc) of the polymer. A method for reducing haze in polymer articles using a co-additive composition in addition to nucleating and clarifying agents is disclosed.

BACKGROUND OF THE INVENTION

Numerous nucleating and clarifying agents are used as plastic additives.Such compounds assist in optically clarifying plastics or otherwiseimproving the processing or physical characteristics of polymers inplastic products. Many plastic products sold and used are made frompolymer materials that contain nucleating or clarifying agents withinthe polymer.

The use of clarifying agents to reduce haze in articles manufacturedfrom crystalline polyolefin resins is well known in the art.Representative acetals of sorbitol and xylitol, which have been employedas clarifying agents, are disclosed generally in the following patents:

Hamada et al., U.S. Pat. No. 4,016,118, dibenzylidene sorbitols

Kawai, et al., U.S. Pat. No. 4,314,039, di(alkylbenzylidene) sorbitols

Mahaffey, Jr., U.S. Pat. No. 4,371,645, diacetals of sorbitols having atleast one chlorine or bromine substituent

Kobayashi, et al., U.S. Pat. No. 4,532,280, di(methyl or ethylsubstituted benzylidene) sorbitols

Rekers, U.S. Pat. No. 5,049,605, bis(3,4-dialkylbenzylidene) sorbitolsincluding substituents forming a carbocyclic ring.

Co-additives have been used in combination with such clarifiers based ondiacetals of sorbitol and xylitol to improve certain properties, suchas:

Mentink, U.S. Pat. No. 6,673,856: discloses co-additives to improve theflow behavior and thermal stability of clarifiers based on diacetals ofsorbitol and xylitols;

Kobayashi, et al., U.S. Pat. No. 6,245,843 discloses using certain“binders” to depress the melting temperature, improving the dispersion,and improving the flow property of clarifiers based on diacetals ofsorbitols and xylitols;

Among clarifiers based on diacetals of sorbitol and xylitol, Millad3988® is a commercially successful clarifier for polypropylene. It is adimethyl substituted dibenzylidene sorbitol (“DMDBS”), 1,3:2,4-bis (3,4dimethyl benzylidene sorbitol). Millad 3988® is manufactured anddistributed by Milliken & Company of Spartanburg, S.C.

Millad 3988® can achieve very good optical properties in polypropylene(“PP”) at its optimum loadings, for example, at loadings near 2500 partsper million (“ppm”). However, its clarifying function is not as greatwhen the loading is relatively low, such as 1000 ppm, for example. Thisis generally true of most clarifiers based on diacetals of sorbitol andxylitol. Though many prior art references have disclosed usingco-additives in combination with such clarifiers to achieve certainbenefits, none of the prior art references known to date have discloseda method and composition that may be employed to improve the clarifyingfunction of such clarifiers at relatively low loadings, namely, toimprove the low level efficacy of these clarifiers.

In some applications, low levels of such clarifiers are highly bedesirable. For example, it will be more economic to use less clarifier,and it will reduce any possible plate out, blooming, or extraction. Amethod, process, or chemical composition that makes it possible toimprove or increase the low level efficacy of nucleating or clarifyingagents is highly desirable. The current invention is directed towardssuch improvements.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of this invention, including the bestmode shown to one of ordinary skill in the art, is set forth in thisspecification. The following Figures illustrate the invention:

FIG. 1 is a sketch of a typical haze curve (haze versus concentration)of a clarifier;

FIG. 2 is a graph showing haze of plastic articles clarified with Millad3988® at various concentrations, under standard processing conditions ina polypropylene random copolymer (RCP) resin;

FIG. 3 shows performance of Millad 3988® and Millad 3988® with PEG 3400as a co-additive (use level of PEG 3400 is 50 ppm) under standardprocessing conditions in a RCP resin;

FIG. 4 depicts the performance of Millad 3988® and Millad 3988® withpolycaprolactone triol (Mn 900) as a co-additive (use level is 50 ppm),under standard processing conditions in a RCP resin;

FIG. 5 illustrates results using Cleartint® Red (use level 1000 ppm) asa co-additive for Millad 3988® in a polypropylene homopolymer (HPP)resin under standard processing conditions;

FIG. 6 shows a haze curve of Millad 3940® and Millad 3940® with 50 ppmpolycaprolactone triol (Mn 900) as co-additive under standard processingconditions in a RCP resin; and

FIG. 7 Shows haze curve of1,3:2,4-bis(4-ethylbenzylidene)-1-allyl-sorbitol and1,3:2,4-bis(4-ethylbenzylidene)-1-allyl-sorbitol with 1000 ppmCleartint® Red as co-additive under standard processing conditions in aHPP resin.

DETAILED DESCRIPTION OF THE INVENTION

Reference now will be made to the embodiments of the invention, one ormore examples of which are set forth below. Each example is provided byway of explanation of the invention, not as a limitation of theinvention. In fact, it will be apparent to those skilled in the art thatvarious modifications and variations can be made in this inventionwithout departing from the scope or spirit of the invention.

To help understanding the current invention, this disclosure defines“critical concentration”. For any clarifiers, it is possible to plothaze levels (it is defined and can be measured according to ASTMD1003-00) of the plastic article versus the concentration of theclarifier in the article. The curve looks typically like the one shownin FIG. 1. Starting with the control haze (A) at 0% clarifierconcentration, haze starts to decrease as the concentration of theclarifier increases. The haze value reaches a minimum (B) when theloading hits its optimum for this particular clarifier. If theconcentration keeps increasing, the haze “levels out”, or starts toincrease if the loading is too high. As a result, this particularclarifier reduces haze of the plastic article by (A-B) units at itsoptimum loading.

The “critical concentration” is the concentration when the decrease ofthe haze is ⅔ of the total haze reduction observed under thoseconditions, namely, the concentration when the haze reduction is2(A−B)/3. The critical haze of the plastic article, at the criticalconcentration, should be [A−2(A−B)/3]=[A+2B]/3. Thus, “criticalconcentration” is a very convenient method to represent the effect of aparticular co-additive on clarifier performance.

For example, FIG. 2 shows the haze of 50 mil polypropylene randomcopolymer (RCP) plaques clarified using Millad 3988® versus theconcentration of Millad 3988® in the system. Control haze (0% clarifier)in this case is 49 (A=49), then it follows the general trend of aclarifier, haze of the plaque starts to decrease as the loading ofMillad 3988® increases. Finally, it reaches the lowest haze of ca. 6.5(B=6.5) at the concentration of 2500-3500 ppm or so. When more Millad3988® is loaded, haze starts to increase. The critical concentration ofMillad 3988 in this RCP resin will be the concentration when the haze ofthe clarified article is [49+2*6.5]/3=20.7. A horizontal line is drawnat 20.7 haze value in FIG. 2, and it intercepts with the haze curve ofMillad 3988 at loading of 1043 ppm. As a result, 1043 ppm is thecritical concentration of Millad 3988 in this RCP resin, and thecritical haze is 20.7.

The critical haze could be understood as a practically acceptable hazein the market for that clarifier, when lower cost is desired. Forexample, Millad 3988® gives an optimum haze of 6.5 at 2500 ppm and it isdesired in many markets where the clarity is extremely important. On theother hand, a haze of 20.7 is acceptable in certain markets where thecost is more sensitive, and only 1043 ppm Millad 3988® is needed forthis purpose. This is just one illustration of the value of thisinvention.

From the above discussion, one can tell that lower criticalconcentration is desired for a clarifier because it indicates a moreefficient clarifier, which achieves critical haze at lower loadings.Therefore, the invention, which helps to identify and evaluate thedecrease in the critical concentration of a clarifier, is desirable.Such a technology enables less clarifier to achieve the same haze, whichis highly desirable when large volumes are processed.

The current invention helps improve the low level efficacy ofdibenzylidene-based nucleating or clarifying agents by using certainco-additives. In more measurable statement, such co-additives helpdecrease the critical concentration of the clarifiers, allowing theclarifiers to achieve fairly good clarification function at lowerconcentration. In at least one example, the critical concentration ofMillad 3988® was cut to almost half by using a co-additive. In thatcase, 545 ppm Millad 3988®, with the help of a co-additive, can achievethe same optical performance of 1043 ppm Millad 3988®.

The current invention is directed toward methods and compositions usingco-additives to increase the low level efficacy, or decrease thecritical concentration of clarifiers. Polymer articles may bemanufactured having one or more co-additives and one or more nucleatingor clarifying agents. Also, a method of reducing critical concentrationin polymer articles using a co-additive composition in addition tonucleating and clarifying agents is also disclosed herein. In someapplications, the polymer composition may be provided with aco-additive, said co-additive having an average molecular weight of 300,or more. In other applications of the invention, a co-additive isprovided which has an average molecular weight of between 400 and10,000,000. Furthermore, plastic or polymeric articles of manufacturemay be constructed from any known method, using the compositions of theinvention. In one aspect of the invention, the co-additive is providedin a concentration of 0.02 parts by weight of less, or alternatively,0.01 or less. The diacetal based clarifier may be provided in a uselevel of 0.15 or less, in some applications. For yet other applications,such as copolymers of ethylene oxide (EO), an average molecular weightof 300-10,000 may be used, and may optionally have a percentage of EO of10-95%. Other embodiments may employ polycaprolactones as co-additives,using average molecular weights of 300-5,000. Some applications of theinvention may employ ionic liquids as co-additives, such as set forthbelow:

wherein R₁, R₂, R₃, R₄, and R₅ are same or different alkyl groups, andthe anion A is selected from the group consisting of: chloride, bromide,tetrafluoroborate, and methosulfates.In yet other applications of the invention, processing may be providedusing techniques of injection molding, extrusion, blow molding,thermoforming, injection stretch blow molding, film casting, or filmblowing.The method of the invention may reduce the critical concentration of thediacetal based clarifier by 10%, by 20%, by 30%, or 40%, or more,depending upon the particular application.At least one application of the invention employs a block copolymer, asfurther described herein. In other applications, the use level of saidco-additive is about 0.05 parts by weight or less, in relation to 100parts by weight of the polyolefin resin.

Thermoplastic Polymers or Copolymers

Polyolefins have been widely used in applications like housewarecontainers, bottles, cups, syringes, pipes, films etc. through variousprocessing methods such as injection molding, extrusion blow molding,thermoforming, casting, etc. In many applications, transparency or seethrough ability is desired. Clarifiers like Millad 3988® are used inthese applications to give the plastic articles the desired opticalproperties. Typical polymers using clarifying or nucleating agents arepolypropylene homopolymer (HPP), polypropylene random copolymer (RCP),polypropylene impact copolymer (ICP). Millad 3988® also clarifies somepolyethylene resins, like linear low-density polyethylene (LLDPE),low-density polyethylene (LDPE), and high-density polyethylene.

The present invention employs certain co-additives to improve the lowlevel efficacy, or decrease the critical concentration of clarifiersbased on diacetals of sorbitol and xylitol. Many tests have been done invarious resins and improvement of optical properties have been observed.

Derivatives of Dibenzylidene

The clarifying agents of interest include diacetals of sorbitol andxylitol having the general formula (I)(I)

where R₁, R₂, R₃, R₄, R₅, R₆, R₇, R₈, R₉, R₁₀ are the same or differentand each represents a hydrogen atom, an alkyl group having 1 to 8 carbonatoms, an alkoxy group having 1 to 4 carbon atoms, an alkoxycarbonylgroup having 1 to 4 carbons, a halogen atom, an hydroxy group, analkylthio group having 1 to 6 atoms, an alkylsulfoxy group having 1 to 6carbon atoms, or a 4 or 5 membered alkyl group forming a carbocyclicring with adjacent carbon atoms of the unsaturated parent ring; nrepresents 0 or 1. Of particular interest are clarifying agents where nis 1 and R₁, R₂, R₃, R₄, R₅, R₆, R₇, R₈, R₉, R₁₀ are selected from C₁₋₄alkyl, chlorine, bromine, thioether and a 4-membered alkyl group forminga carbocyclic ring with adjacent carbon atoms of the unsaturated parentring. Examples of specific clarifiers include: dibenzylidene sorbitol,di(p-methylbenzylidene) sorbitol, di(o-methylbenzylidene) sorbitol,di(p-ethylbenzylidene) sorbitol, bis(3,4-dimethylbenzylidene) sorbitol,bis(3,4-diethylbenzylidene) sorbitol,bis(5′,6′,7′,8′-tetrahydro-2-naphthylidene) sorbitol,bis(trimethylbenzylidene) xylitol, and bis(trimethylbenzylidene)sorbitol. Also within the scope of the present invention are compoundsmade with a mixture of aldehydes, including substituted andunsubstituted benzaldehydes, such as Kobayashi, et al., U.S. Pat. No.4,532,280 and Kobayashi, et al., U.S. Pat. No. 4,954,291.

The clarifying agents of interest also include diacetals of sorbitol andxylitol having the general formula (II).

where R is selected from the group consisting of: alkenyls, alkyls,alkoxys, hydroxyl alkyls, and haloalkyls, and derivatives thereof; R₁,R₂, R₃, R₄, R₅, R₆, R₇, R₈, R₉, R₁₀ are the same or different and eachrepresents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms,an alkoxy group having 1 to 4 carbon atoms, an alkoxycarbonyl grouphaving 1 to 4 carbons, a halogen atom, an hydroxy group, an alkylthiogroup having 1 to 6 atoms, an alkylsulfoxy group having 1 to 6 carbonatoms, or a 4 or 5 membered alkyl group forming a carbocyclic ring withadjacent carbon atoms of the unsaturated parent ring; n represents 0or 1. Of particular interest are clarifiers where R is methyl, ethyl,propyl, butyl, allyl, or crotyl, R₁, R₂, R₃, R₄, R₅, R₆, R₇, R₈, R₉, R₁₀are selected from C₁₋₄ alkyl, chlorine, bromine, thioether and a4-membered alkyl group forming a carbocyclic ring with adjacent carbonatoms of the unsaturated parent ring. Examples of specific clarifiersinclude: 1,3:2,4-bis(4-ethylbenzylidene)-1-allyl-sorbitol,1,3:2,4-bis(3′-methyl-4′-fluoro-benzylidene)-1-propyl-sorbitol,1,3:2,4-bis(5′,6′,7′,8′-tetrahydro-2-naphthaldehydebenzylidene)-1-allyl-xylitol,bis-1,3:2-4-(3′,4′-dimethylbenzylidene)-1″-methyl-1-propyl-sorbitol, and1,3:2,4-bis(3′,4′-dimethylbenzylidene)-1-propyl-xylitol.

Co-Additives

Various co-additives can be employed in the practice of the invention.The examples and Tables herein list only a few of the co-additives thatcan be used in the practice of the invention, and the practice and scopeof the invention is not limited to only those species recited herein.Further, there are many, many different DBS derivatives that could beemployed, and the invention is not limited to any particular DBSderivative for application of the co-additives of the invention.

In the present invention, co-additives used to improve the low levelefficacy of clarifiers containing at least one member selected from thegroup consisting of (a) poly(ethylene glycol) and their derivatives likepoly(ethylene glycol) alkyl ether, poly(ethylene glycol) alkyl ester;(b) copolymers containing segments of ethylene oxide, such asblockcopolymers of ethylene oxide and propylene oxide, blockcopolymersof poly(ethylene glycol) and another polymer such as, but not limitedto, polyethylene, polypropylene, polystyrene, poly(dimethylsiloxane), orpolycaprolactone; (c) poly(vinyl alcohol), poly(allyl alcohol), andblockcopolymers of poly(vinyl alcohol) or poly(allyl alcohol), a fewexamples are poly(styrene-co-allyl alcohol), poly(vinyl alcohol-co-vinylacetate), and poly(vinyl alcohol-co-ethylene); (d) polycaprolactonederivatives like polycaprolactone diol, polycaprolactone triol,polycaprolactone tetraol; (e) polyesters based on aliphatic di-alcoholsand aliphatic di-carboxylic acid, examples include, but not limited to,poly(ethylene azelate), poly(ethylene succinate), poly(1,3-propylenesuccinate), poly(1,3 propylene adipate), poly(ethylene adipate),poly(1,4-butylene adipate), poly(di(ethylene glycol) adipate); (f)polycarbonate and derivatives like poly(polytetrahydrofuran carbonate)diol, poly(hexamethylene carbonate), poly(propylene carbonate); g)polyamines like polyethyleneimine; h) ionic liquid based on imidazolechemistry, i) lithium containing compounds like lithium chloride,lithium bromide, lithium stearate, lithium lactate, lithiumtrifluoromethanesulfonate, and lithium benzoate; j) any mixers of theabove compounds.

FIG. 2 shows a plot of haze versus loading level for Millad 3988® ofinjection molded 50 mil plaques, under standard processing conditionswithout co-additives. Standard processing conditions refer to a) mixingall components in a high intensity mixer for 1 minute; b) compoundingthe mixed powder using a single screw extruder at ca. 230 degrees C.; c)molding the compounded resin into 50 mil plaques at 230 degrees C. and2.4 cc/second injection rate; d) resin used is a polypropylene randomcopolymer, RCP SA849. The critical concentration of Millad 3988 in thisresin under the standard processing conditions is 1040 ppm, as mentionedabove. The following examples demonstrate how the current inventiondecreases the critical concentration of Millad 3988, namely allowingless amount of Millad 3988 to achieve the same haze.

EXAMPLE 1 PEG3400 as a Co-Additive for Millad 3988® in a RCP Resin

PEG 3400 is employed as a co-additive in this example. PEG 3400 ischemically known as poly(ethylene glycol), and 3400 refers to theaverage molecular weight of this particular grade. The general chemicalstructure of PEG is

where n is the repeating unit. The value of n determines the molecularweight of the polymer. Such structure is also termed PEO aspoly(ethylene oxide) when molecular weight is high.

PEG 3400 was added to the formulation at 50 ppm along with a certaingiven loading of Millad 3988®. The haze performance of this formulationwas then compared with Millad 3988 without co-additive at the sameloading. Both formulations were processed under standard processingconditions. FIG. 3 shows the comparison between the two.

Millad 3988® at 50 ppm with PEG 3400 shows less haze than Millad 3988®alone at all loadings tested (500, 750, 1000 and 1250 ppm). At 500 ppmof Millad 3988®, haze reduction is ca. 12 haze units; at 750 ppm ofMillad 3988®, haze reduction is ca. 11 haze units; at 1000 ppm of Millad3988®, haze reduction is ca. 8 haze units; at 1250 ppm of Millad 3988®,haze reduction is ca. 1.5 haze units. An improvement of 2 haze units isvisible to human eyes. Such improvement is significant and unexpected,given that only 50 ppm PEG 3400 was used. The critical concentration forthis new formulation, Millad 3988® with 50 ppm PEG3400, is 545 ppm basedon the calculation. Namely, 545 ppm Millad 3988® with the help of 50 ppmPEG3400, achieved a haze of 20.7, which could only be achieved by 1043ppm Millad 3988 if used alone. From 1043 ppm to 545 ppm, the criticalconcentration is reduced by 48%!

This example used one conditions, which is termed standard condition.This is listed as one example and the current invention applies to otherprocessing conditions as well. For example, this co-additive formulationwas also tested at 200 degrees C. molding temperature, while otherprocessing conditions were kept the same. The extent of haze reductionfor Millad 3988® is similar for loadings from 500 ppm to 1250 ppm. Ifmixing conditions changes from high intensity mixing to low intensitymixing, the extent of haze reduction by using this co-additiveformulation still holds the same.

The low level efficacy of Millad 3988® has been dramatically improvedafter using a very small amount of co-additive, 50 ppm PEG 3400. SeveralPEG or PEO grades with different molecular weights were tested also, andfor PEG or PEO compounds with the average molecular weight equal to orlarger than 600, they work well as co-additives to improve the low levelefficacy or decrease the critical concentration of Millad 3988®. PEG1000 (1000 refers to the average molecular weight of this PEG grade) isabout the same as PEG 3400 in terms of improving the low level efficacyof Millad 3988. Both are the best among the group tested.

EXAMPLE 2 Polycaprolactone Triol as a Co-Additive for Millad 3988® in aRCP Resin

Polycaprolactone triol (Mn=900) was used as a co-additive for Millad3988® in this example to decrease its critical concentration. Generalchemical structure of polycaprolactone triol is as follows:

where m, n, p stand for the number of repeating units for each strand,and they could be same or different. The average molecular weight of theparticular grade used is ca. 900 g/mol and is a waxy material at roomtemperature. 50 ppm of polycaprolactone triol was added to theformulation in liquid after being preheated at 60 degrees C. Both Millad3988® formulations with and without co-additive were extruded at 230Cusing a single screw extruder and molded at 230 degrees C. in a randompolypropylene copolymer, RCP SA849.

FIG. 4 shows the haze curve of Millad 3988® without and withpolycaprolactone triol (Mn 900) as a co-additive. It dramaticallyimproves the low level efficacy of haze performance for Millad 3988®.The extent of improvement is similar as PEG 3400, as discussed inExample 1. Calculation of the critical concentration in this caseresulted in 615 ppm, namely, 615 ppm Millad 3988 with 50 ppmpolycaprolactone triol (Mn 900) can achieve 20.7 haze, which could onlybe achieved by using 1043 ppm Millad 3988® alone. From 1043 ppm to 615ppm, the critical concentration is reduced by 41%.

This co-additive formulation was also tested at 200 degrees C. moldingtemperature, while other processing conditions were kept the same. Theextent of haze reduction for Millad 3988® is similar for loadings from500 ppm to 1250 ppm.

Polycaprolactone triol with different molecular weights and severalpolycaprolactone diols and tetraols with various molecular weights werealso tested. Most of them work well as co-additives to improve the lowlevel efficacy of Millad 3988®. Among all the samples tested in thisclass, polycaprolactone triol (Mn=900) and polycaprolactone diol(Mn=1250) are among the best. The chemical structure of polycaprolactonediol is as follows,

The chemical structure of polycaprolactone tetraol is as follows,

EXAMPLE 3 Cleartint® Red as a Co-Additive for Millad 3988® in a HPPResin

This example employs Cleartint® Red and its corresponding coupler asco-additives. Reference is made to FIG. 5.

Cleartint® Red is a polymeric colorant product produced and manufacturedby Milliken & Company of Spartanburg, S.C., USA. 1000 ppm Cleartint® Redwas added as masterbatch and Hobalt mixed and single screw compounded.The formulation was then molded at 230 degree C. In this case, apolypropylene homopolymer was used as the base resin. Haze curve ofMillad 3988®, and Millad 3988® with 1000 ppm Cleartint® Red asco-additive is shown in FIG. 5. For Millad 3988® alone, control hazeA=56.2, and the optimum haze=9.2, and the criticalhaze=[56.2+2*9.2]/3=24.9. Critical concentration is, as shown in FIG. 5,1273 ppm. In the case of Millad 3988® with 1000 ppm Cleartint® Red asco-additive, the critical concentration is reduced to 687 ppm. With thehelp of 1000 ppm Cleartint® Red, 687 ppm can achieve the critical hazeof 24.9, which could be achieved by 1273 ppm Millad 3988®. From 1273 ppmto 687 ppm, it is a 46% in critical concentration! As a result, lowlevel efficacy of Millad 3988® is highly improved by using co-additiveslike Cleartint® Red.

Other Cleartint® colors were also tested and they are good co-additivesfor improving the low level efficacy or reducing the criticalconcentration of Millad 3988®

A certain color is obtained when a certain chromophore is attached tothe benzene ring of the coupler structure, which is shown below, where“EO” denotes an ethylene oxide moiety, and “PO” denotes a propyleneoxide moiety:

However, it is recognized that the two moieties attached to the Nitrogencould be also designated as R₁ and R₂, wherein R₁ and R₂ are selectedindependently, and each comprise one or more EO or PO groups.

Couplers themselves can also be used as co-additive for Millad 3988® toimprove its low level efficacy or decrease its critical concentration.Many couplers were tested, and some of them reduced the criticalconcentration in a similar manner as Cleartint® Red.

EXAMPLE 4 Polycaprolactone Triol as a Co-Additive for Millad 3940® in aRCP Resin

This example employs polycaprolactone triol (Mn=900) as a co-additivefor Millad 3940® in a polypropylene random copolymer resin. Millad 3940®is a product of Milliken & Company, chemically it is known as1,3:2,4-bis(4-methylbenzylidene)-sorbitol, or MDBS. Polycaprolactonetriol was introduced to the formulation at 50 ppm. Haze curve of Millad3940@ with and without polycaprolactone triol is shown in FIG. 6. Inthis case, A=49.0, B=8.0, and the critical haze is [49.0+2*8.0]/3=21.7.The critical concentration of Millad 3940® is 936 ppm. With the help of50 ppm polycaprolactone triol (Mn 900), the critical concentration isreduced to 724 ppm, it is a 23% reduction. In conclusion,polycaprolactone triol improved the low level efficacy of Millad 3940®.

EXAMPLE 5 Cleartint® Red as a Co-Additive for1,3:2,4-bis(4-ethylbenzylidene)-1-allyl-sorbitol in a HPP Resin

This example uses Cleartint® Red as a co-additive for1,3:2,4-bis(4-ethylbenzylidene)-1-allyl-sorbitol in a HPP resin.Cleartint® Red is a polymeric colorant manufactured and distributedcommercially by Milliken and Company of Spartanburg, S.C. The Cleartint®Red was added using masterbatch and the final loading is 1000 ppm. Hazecurve of 1,3:2,4-bis(4-ethylbenzylidene)-1-allyl-sorbitol with andwithout the co-additive is shown in FIG. 7. It is obvious that low levelefficacy of this clarifier is improved after introducing the co-additiveto the formulation. The critical concentration of the clarifier alone is1908 ppm, while with the help of the co-additive, the criticalconcentration is reduced to 1187 ppm, a 38% reduction in criticalconcentration.

Other kinds of Cleartint® color and their couplers were also tested andmost of them work very well as co-additives to improve the low levelefficacy or reduce the critical concentration for this clarifier.

EXAMPLE 6 Other Co-Additives for Millad 3988® in a RCP Resin

In addition to the examples discussed above, numerous materials havebeen tested, and some of the results are listed in Table 1. A RCP resinwas employed and standard processing conditions were used to makeplastic parts for haze measurements. For all examples in Table 1, tosimplify the experiments, only one loading of Millad 3988® was tested.Millad 3988® was set to 1000 ppm, and the co-additive loading is listedin the table. Haze values of 1000 ppm Millad 3988®, and 1000 ppm Millad3988® with the co-additive, are listed in the table. The difference iscalculated and shown in the table as well. Negative number indicates ahaze reduction by using the co-additive, and is desired. A hazereduction of 2 or more is considered significant and a haze reduction of6 or more is great. As from the previous Examples 1-3, when theco-additive reduces haze for 1000 ppm Millad 3988®, they typicallyreduces haze of other loadings of Millad 3988® as well, for example,from 500 to 1250 ppm. Though critical concentration was not calculatedfor these examples listed here, similar results (reducing criticalconcentration) to those co-additives in Examples 1 to 3 are expected.Furthermore, such examples are not limiting the application of them toother DBS-based clarifying agents. It is a logical expectation thatthese co-additives also reduces the critical concentration or improvethe low level efficacy of other DBS-based clarifying agents, like thoseco-additives in Example 4 and 5.

Group I (No. I-1 to I-11) co-additives are based on poly(ethyleneglycol), blockcopolymers containing at least one block of poly(ethyleneglycol), and the random copolymer of ethylene oxide and propylene oxide.In certain cases, various molecular weight of one class was tested. Forexample, poly(ethylene glycol) of various molecular weight (from 600 to8,000,000) was tested and all of them are very good at reducing haze(equal to or over 5 units) for 1000 ppm Millad 3988®. Several block andrandom copolymers of PEG and PPG (various ratio and molecular weight)were tested and two of them are listed in Table 1 (No. I-8 and I-9). Allthe block and random copolymers of PEG and PPG tested are very goodco-additives for reducing haze of 1000 ppm Millad 3988®.Poly(dimethylsiloxane) ethoxylate/propoxylate is a block copolymer ofpolydimethylsiloxane, poly(ethylene glycol) and poly(propylene glycol)and is also a very effective co-additive for Millad 3988® at reducinghaze, and so is the poly(ethylene)-block-poly(ethylene glycol). One cansummarize that poly(ethylene glycol) is the functional part, whichreduces the haze of Millad 3988®. As a result, it is very reasonable toexpect that any copolymers containing segments of ethylene oxide willhave similar function, namely, reducing the haze or criticalconcentration of Millad 3988®. TABLE 1 Haze Difference of (□ haze) 1000ppm Millad 3988 ® Without and with Co-Additives, negative numberindicates a haze reduction Loading of Number Co-additive Co-additive(ppm) Δ haze Group 1 co-additive examples in Example 6 1-1 PEG600 100−5.3 1-2 PEG900 100 −6.0 1-3 PEG1000 100 −6.7 1-4 PEG8000 100 −5.1 1-5PEO100,000 100 −5.0 1-6 PEO900,000 100 −6.1 1-7 PEO8,000,000 25 −7.3 1-8PEO-block-PPO-block-PEO (Mn 1900, 50% EO) 50 −6.6 1-9Poly(ethyleneglycol-ran-propylene glycol) 100 −4.5 (Mn 2500)  1-10Poly(dimethylsiloxane) ethoxylate/propylate 50 −7.0  1-11Polyethylene-block-poly(ethylene glycol) 250 −5.1 50% EO, Mn 920 Group 2co-additive examples in Example 6 2-1 Poly(ethylene glycol) dioleate1500 −6.4 2-2 Poly(ethylene glycol) monooleate 500 −6.7 2-3Poly(ethylene oxide) 4-nonylphenyl 3- 50 −5.3 sulfopropyl ether, K 2-4Poly(oxyethylene) oleyl ether (Mn 1150) 50 −5.7 2-5 Polyoxyethylenesorbitol hexaolate 50 −6.5 2-6 Polyoxythylene sorbitan tetraoleate 50−3.9 Group 3 co-additive examples in Example 6 3-1 Polystyrene-co-allylalcohol 100 −6.4 3-2 Poly(vinyl alcohol-co-vinyl acetate) 50 −6.4 3-3Poly(vinyl alcohol-co-ethylene) 50 −4.8 Group 4 co-additive examples inExample 6 4-1 Poly(ethylene azelate) 50 −4.3 4-2 Poly(1,3-propylenesuccinate) 50 −4.4 4-3 Poly(ethylene adipate) 50 −6.7 4-4Poly(1,3-propylene adipate) 50 −7.8 4-5 Poly(1,4-butyl adipate) 50 −3.54-6 Poly[di(ethylene glycol) adipate] 50 −4.3 4-7 Polycaprolactone 50−2.7 4-8 Polycaprolactone diol (Mn 530) 50 −5.6 4-9 Polycaprolactonetetraol (Mn 1000) 50 −5.7  4-10Polycaprolactone-block-polytetrahydrofuran- 50 −6.4 blockPolycaprolactone Group 5 co-additive examples in Example 6 5-1Poly(polytetrahydrofuran carbonate) diol 50 −6.9 5-2 Poly(hexamethylenecarbonate) diol 50 −4.6 Group 6 co-additive examples in Example 6 6-1polyethyleneimine 50 −6.3 6-2 Poly[(o-cresyl glycidylether)-co-formaldehyde] 50 −4.6 (Mn 1080) Group 7 co-additive examplesin Example 6 7-1 Lithium chloride 50 −3.1 7-2 Lithium benzoate 50 −3.67-3 Lithium lactate 50 −3.4 7-4 Lithium trifluoromethanesulfonate 50−3.8 7-5 Lithium stearate 200 −3.1 Group 8 co-additive examples inExample 6 8-1 Fluorad FC-430 100 −4.0 Group 9 co-additive examples inExample 6 9-1 1-ethyl-3-methylmidazolium chloride 50 −5.6 9-21-hexyl-3-methylimidazolium chloride 50 −3.0

Group 2 co-additives (No. 2-1 to 2-6) are poly(ethylene glycol)derivatives. They include, but not limited to, poly(ethylene glycol)alkyl ether, poly(ethylene glycol) alkyl ester. For example,poly(ethylene glycol) oleyl ether, and poly(ethylene glycol) monooleatewere tested as co-additives and they are very effective in terms ofreducing haze for 1000 ppm Millad 3988® (over 5 units). The authorsbelieve that the poly(ethylene glycol) chemistry is the key part, whichfunctions as reducing haze for Millad 3988®, and most compoundscontaining poly(ethylene glycol) as a part are likely going to be goodco-additives for Millad 3988® to reduce its critical concentration. Forthose skilled in the art, it is logical to expect other materials withsimilar structure will also be effective co-additives for reducing hazeof Millad 3988®, such as poly(ethylene glycol) fatty ethers,poly(ethylene glycol) fatty esters, phosphate esters with at least onearm containing segments of ethylene oxide, polyoxyethylene sorbitolhexaolate, polyoxythylene sorbitan tetraoleate.

Group 3 co-additives (No. 3-1 to 3-3) are polyalcohols and theirblockcopolymers. Poly(vinyl alcohol-co-vinyl acetate) and poly(vinylalcohol-co-ethylene) are both good co-additives for Millad 3988® interms of reducing haze. Polystyrene-co-allyl alcohol is also a very goodone, reducing haze by 6.4 units. For those skilled in that art, it islogical to expect that polymers or copolymers containing one or moreblocks of vinyl alcohol or allyl alcohol are going to be goodco-additives for Millad 3988® in terms of improving its clarificationfunction at relatively low loadings.

Group 4 co-additives (No. 4-1 to 4-10) are polyesters and theirderivatives. Polycaprolactone itself is a moderate co-additive, reducinghaze by 2.7 units. On the other hand, its derivatives, likepolycaprolactone diol, polycaprolactone triol, and polycaprolactonetetraol, are fairly good co-additives for Millad 3988® in terms ofimproving its haze performance. As for polyesters based on aliphaticdi-alcohols and aliphatic di-carboxylic acids, many of them are veryeffective in reducing haze of 1000 ppm Millad 3988®, such aspoly(1,3-propylene adipate), poly(ethylene adipate), etc. Examples 2 and4 have shown more detailed study of polycaprolactone triol (Mn 900). Itis a reasonable expectation that copolymers containing these chemistrymentioned here, as well as derivatives of them, are also going to begood co-additives for Millad 3988® in terms of improving its low levelefficacy.

Group 5 co-additives (No. 5-1 to 5-2) are polycarbonate derivatives.Among them, poly(polytetrahydrofuran carbonate) diol is the best,reducing haze by 6.9 haze units for 1000 ppm Millad 3988®.

Group 6 co-additives (No. 6-1 to 6-2) are other type oligomers/polymers.Both polyethyleneimine and poly[o-cresyl glycidylether)-co-formaldehyde] are effective in terms of reducing haze for 1000ppm Millad 3988®.

Group 7 co-additives (No. 7-1 to 7-5) are small molecular compounds.Lithium containing compounds reduces haze about 3 units for 1000 ppmMillad 3988®. Generally, they are not as effective as the best in Group1-6, where co-additives are oligmers/polymers.

Group 8 co-additives (No. 8-1) are fluoro-containing surfactants, likeFluorad FC-430 (a commercial offering from Fluorochem Ltd.), whichreduces 4 haze units for 1000 ppm Millad 3988®.

Group 9 co-additives (No.9-1 to 9-2) are ionic liquids based onimidazole chemistry. Two examples are given in the table and the betterone, 1-ethyl-3-methylmidazolium chloride, reduces haze of 5.6 haze for1000 ppm Millad 3988®.

In summary, the authors have found many compounds can be used asco-additives to help improve the haze performance of Millad 3988® inpolypropylene resins. As a result, low level efficacy of Millad 3988® isdramatically improved and the critical concentration is greatly reduced.Such significant improvement by using a co-additive is unexpected and isa novel invention. The optimum use level of many co-additives is only 50ppm, while the range of 10 ppm to 100 ppm works pretty well for mostco-additives.

EXAMPLE 7 PEG3400 and polycaprolactone triol (mn 900) as Co-Additivesfor Millad 3988® in a LLDPE Resin

In addition to Example 1-6 where the current invention was targeted atpolypropylene resins, it also applies to polyethylene resins like linearlow density polyethylene (LLDPE). Dowlex 2517 is a well known LLDPEgrade in the market, and was employed as the base resin. Millad 3988® isthe clarifying agent, co-additives tested include PEG 3400,polycaprolactone triol (Mn 900). Standard processing conditions wereused and 50 mil injection molded plaques were made to measure opticalproperties. The results are listed in Table 2. TABLE 2 Haze performanceof Millad 3988 with and without co- additives in LLDPE (Dowlex 2517)1000 ppm 1000 ppm Millad 3988/ Millad 1000 ppm Millad 3988/ 50 ppmpolycaprolactone 3988 50 ppm PEG3400 triol (Mn 900) haze 54.6 49.3 47.3

Based on the results of Table 2, co-additives can also be used to reducethe haze of Millad 3988® in LLDPE, ca. 5-7 haze units, when loading ofMillad 3988® is at 1000 ppm loading. Co-additives, which are effectivein improving low level efficacy of Millad 3988® in polypropylene resins,are likely effective in doing the same job in polyethylene resins whereMillad 3988® is a clarifier. Furthermore, these co-additives areexpected to help other diacetal based clarifiers in polyethylene resins,such as bis(2,4-dimethylbenzylidene) sorbitol and its asymmetric blendwith benzylidene sorbitol.

COMPARATIVE EXAMPLE 1 Poly(propylene glycol) as Co-Additive for Millad3988® in a RCP Resin

Poly(propylene glycol) (average molecular weight is 425) was used inthis example as a co-additive for Millad 3988®. 1000 ppm Millad 3988®without co-additive and with co-additive (loading various from 20 ppm to1000 ppm) were processed under standard conditions. When comparing thehaze performance, poly(propylene glycol) only reduces haze by 2 units atbest, and several loadings only help less than 2 units. Based on thisresult, PPG is not an effective co-additive to help the haze performanceof Millad 3988®.

COMPARATIVE EXAMPLE 2 Poly(oxymethylene) as Co-Additive for Millad 3988®in a RCP Resin

A grade of poly(oxymethylene) was used in this example as a co-additivefor Millad 3988®. 1000 ppm Millad 3988® without co-additive and withco-additive (loading various from 50 ppm to 500 ppm) were processedunder standard conditions. When comparing the haze performance,poly(oxymethylene) did not reduces haze at all, it actually increaseshaze by over 3 units of 1000 ppm Millad 3988®.

Combining Example 1 and Comparative Example 1 and 2, not all thepolyether chemistry works as co-additive for Millad 3988®. Whilepoly(ethylene glycol) is very effective to improve the haze performanceof Millad 3988®, poly(propylene glycol) is very effective, andpoly(oxymethylene) actually deteriorates the haze performance of Millad3988®.

COMPARATIVE EXAMPLE 3 Sodium dodecyl sulfate, Tween 80, and Span 80 asCo-Additives for Millad 3988® in a RCP Resin

Sodium dodecyl sulfate, Tween 80, and Span 80 were used in this exampleas co-additives for Millad 3988®. 1000 ppm Millad 3988® withoutco-additive and with co-additive (loading is 50 ppm) were processedunder standard conditions. When comparing the haze performance, All thethree co-additives do not change the haze of 1000 ppm Millad 3988®.These three materials are known to be good surfactants, and apparently,not all good surfactants work well as co-additives to improve the hazeperformance of Millad 3988®.

COMPARATIVE EXAMPLE 4 Poly(vinylidene fluoride) as Co-Additive forMillad 3988® in a RCP Resin

Poly(vinylidene fluoride) was used in this example as a co-additive forMillad 3988®. 1000 ppm Millad 3988® without co-additive and withco-additive (loading various from 50 ppm to 500 ppm) were processedunder standard conditions. When comparing the haze performance,poly(vinylidene fluoride) increases the haze of 1000 ppm Millad 3988® by1 unit or more. While fluoro-containing surfactant works as a goodco-additive for Millad 3988® (Group 8 in Example 6), thisfluoro-containing polymer did not work at all in this aspect.

COMPARATIVE EXAMPLE 5 Poly(ethylene terephthalate) and poly(butylenesterephthalate) as Co-Additives for Millad 3988® in a RCP Resin

Poly(ethylene teraphthalate) and poly(butylenes teraphthalate) were usedin this example as co-additives for Millad 3988®. 1000 ppm Millad 3988®without co-additive and with co-additive (loading is 50 ppm) wereprocessed under standard conditions. When comparing the hazeperformance, both co-additives did not help the haze of 1000 ppm Millad3988®. While many polyesters are effective co-additives (Group 4 inExample 6) for Millad 3988® to improve its haze performance, these twocommon polyesters tested in this examples do not work in this aspect.

Summary of Results

While most examples shown above are focused on Millad3988® andpolypropylene resin, this invention applies to other diacetal basedclarifiers, and to other types of polyolefin resins. Many goodco-additives are listed, and it is a logical expectation that mixturesof them, derivatives of them, and copolymers containing them, are likelyto be good co-additives as well, in terms of improving the hazeperformance or reducing the critical concentration of the diacetal basedclarifiers,

It is understood by one of ordinary skill in the art that the presentdiscussion is a description of exemplary embodiments only, and is notintended as limiting the broader aspects of the present invention, whichbroader aspects are embodied in the exemplary constructions. Theinvention is shown by example in the appended claims.

Test Method of Critical Concentration and the Calculation of theCritical Concentration Reduction

Many examples given above have discussed the concept of criticalconcentration and the reduction of it by using certain co-additives.This test method may be applied in determining the criticalconcentration reduction observed.

A polypropylene random copolymer, RCP SA849, is used as the resin. For agiven diacetal based clarifier and a given co-additive, the followingprocedure will be used to measure the critical concentrations of boththis clarifier and the clarifier with the help of the co-additive.

I. To create the haze curve for this clarifier in SA849 under standardprocessing conditions.

(a) Mix all components, SA849 fluff, Irganox1010 (recommended loading:500 ppm) and Irgafos168 (recommended loading: 1000 ppm) asanti-oxidants, calcium stearate as acid scavenger (recommended loading:800 ppm), a certain loading of the clarifier, using a high intensitymixer, like Henshel, for 1 minute.

(b) The mixer is then extruded at 230C using a single screw extruder,such as a 30:1 Deltaplast extruder.

(c) The resulted pellets are then molded into twelve 50 mil plaquesusing a 40 ton Auburg molder, at 2.4 cc/s injection rate, 230C moldingtemperature, 21C mold temperature, and a highly polished mold.

(d) Haze of all 12 plaques is read using a haze meter, like a BYKGardner haze meter, and the average is taken as the haze value for thisloading of the clarifier in SA849.

(e) Various loadings of the clarifier are tested using steps from (a) to(d), for example, 0 ppm, 500 ppm, 750 ppm, 1000 ppm, 1500 ppm, 2000 ppm,2500 ppm, 3500 ppm, 5000 ppm, 7500 ppm, etc. and the haze value of eachloading is measured, and a haze curve is then created, just like the onein FIG. 1. The key is to make sure that the highest loading is highenough that the haze curve has a minimum point, which is the optimumhaze of this clarifier.

II. To obtain the critical concentration of the clarifier from the hazecurve build above.

(a) Read the control haze (A) and the optimum haze (B) from the hazecurve build above, and calculate the critical haze, which equals[A+2B]/3.

(b) Draw a horizontal line along the critical haze to intercept with thehaze curve build above, and the concentration at the interception is thecritical concentration, as shown in FIG. 1. Let's call this criticalconcentration “X”.

III. To establish the haze curve for Millad 3988 with the help of theco-additive under exactly the same processing conditions as stated in(1). The only difference is to include a certain amount of theco-additive in each formulation (for example, 50 ppm).

IV. To obtain the critical concentration of the clarifier/co-additivefrom the haze curve of it using the same steps as in II. The criticalconcentration of the Millad 3988/co-additive is termed “Y”.

V. To calculate the percentage change of the critical concentration. Thereduction percentage of the critical concentration by using 50 ppmco-additive is [X−Y]/X*100%.

VI. From examples listed above, most examples work well at 50 ppm, whilesome work well at higher loadings, like 100 ppm, or even 1000 ppm, suchas Cleatint Red®. In case 50 ppm co-additive does not provide an over10% critical concentration based on results from V, this co-additiveshould be tested also at 100 ppm, 250 ppm, 500 ppm, 1000 ppm,respectively. If all the testing results do not show that theco-additive reduces the critical concentration by over 10%, the authorsconclude that this co-additive is not an effective co-additive in termsof improving the low level efficacy of this clarifier. On the otherhand, if in one case, the reduction of the critical concentration isover 10%, then the authors conclude that this co-additive is aneffective co-additive in terms of improving the low level efficacy ofthis clarifier. Such clarifiers are covered in this invention, and theclaims show more details.

1. A method to prepare a plastic composition, said composition being adapted for reducing the critical concentration of diacetal based clarifiers by at least 10%, said method comprising (a) providing at least one polyolefin resin, (b) providing at least one diacetal represented by formula (I)

wherein R is selected from the group consisting of: hydrogen atom, alkenyls, alkyls, alkoxys, hydroxyl alkyls, and haloalkyls; R₁, R₂, R₃, R₄, R₅, R₆, R₇, R₈, R₉, R₁₀ are the same or different and each may represent one of the following: a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an alkoxycarbonyl group having 1 to 4 carbons, a halogen atom, an hydroxy group, an alkylthio group having 1 to 6 atoms, an alkylsulfoxy group having 1 to 6 carbon atoms, or a 4-5 membered alkyl group forming a carbocyclic ring with adjacent carbon atoms of the unsaturated parent ring; and ps n represents 0 or 1; (c) providing at least one co-additive selected from the group consisting of: poly(ethylene glycol), poly(ethylene glycol) derivatives, copolymers containing segments of ethylene oxide, polyalcohols and their derivatives, blockcopolymers containing at least on block of a polyalcohol, polycaprolactone derivatives and their copolymers, polyesters based on aliphatic di-alcohols and aliphatic di-carboxylic acids as well as copolymers of these polyesters, polycarbonate derivatives and their copolymers, polyethyleneimine, and ionic liquids, said co-additive having an average molecular weight of 300 or more; (d) combining (a),(b) and (c) to form a combination; and (d) processing said combination into an article.
 2. A method according to claim 1 wherein the polyolefin resin comprises at least one member selected from the group consisting of: polypropylene random copolymer, polypropylene homopolymer, polypropylene impact copolymer, linear low density polyethylene, low density polyethylene, and high density polyethylene.
 3. A method according to claim 1 wherein the polyolefin resin comprises at least one member selected from the group consisting of polypropylene random copolymer and polypropylene homopolymer.
 4. A method according to claim 1 wherein said diacetal comprises at least one member selected from the group consisting of dibenzylidene sorbitol, di(p-methylbenzylidene) sorbitol, di(o-methylbenzylidene) sorbitol, di(p-ethylbenzylidene) sorbitol, bis(3,4-dimethylbenzylidene) sorbitol, bis(3,4-dichlorobenzylidene) sorbitol, bis(3,4-diethylbenzylidene) sorbitol, bis(5′,6′,7′,8′-tetrahydro-2-naphthylidene) sorbitol, bis(trimethylbenzylidene) xylitol, and bis(trimethylbenzylidene) sorbitol.
 5. A method according to claim 1 wherein said diacetal comprises at least one member selected from the group consisting of di(p-methylbenzylidene) sorbitol and bis(3,4-dimethylbenzylidene) sorbitol.
 6. A method according to claim 1 wherein the use level of said diacetal based clarifier is 0.15 parts by weight or less, in relation to 100 parts by weight of the polyolefin resin.
 7. A method according to claim 6 wherein the use level of the co-additive is 0.02 parts by weight or less, in relation to 100 parts by weight of the polyolefin resin.
 8. A method according to claim 6 wherein the use level of the co-additive is 0.01 parts by weight or less, in relation to 100 parts by weight of the polyolefin resin.
 9. A method according to claim 1 wherein the use level of the diacetal based clarifier is 0.1 parts by weight or less, in relation to 100 parts by weight of the polyolefin resin.
 10. A method according to claim 9 wherein the use level of the co-additive is 0.02 parts by weight or less, in relation to 100 parts by weight of the polyolefin resin.
 11. A method according to claim 9 wherein the use level of the co-additive is 0.01 parts by weight or less, in relation to 100 parts by weight of the polyolefin resin.
 12. A method according to claim 1 wherein the co-additive is selected from the group consisting of poly(ethylene glycol) and the average molecular weight is between about 400 and about 10,000,000.
 13. A method according to claim 1 where in the co-additive is selected from the group consisting of poly(ethylene glycol) and the average molecular weight is between about 600 and about 10,000.
 14. An article of manufacture made by employing the method of claim
 1. 15. A method according to claim 1 wherein the co-additive is selected from the group consisting of: poly(ethylene glycol) derivatives, poly(ethylene glycol) alkyl ether, poly(ethylene glycol) alkyl phenyl ether, poly(ethylene glycol) alkyl ester, poly(ethylene glycol) glycerin fatty acid esters, poly(ethylene glycol) sorbitan fatty acid ester, poly(ethylene glycol) sorbitol fatty acid esters, and phosphate esters with at least one arm comprising of segments of ethylene oxide; wherein the average molecular weight of said co-additive is from about 300 to about 10,000.
 16. A method according to claim 1 wherein the co-additive is a copolymer of ethylene oxide, and is selected from the group consisting of: block copolymers of ethylene oxide and propylene oxide, random copolymers of ethylene oxide and propylene oxide, blockcopolymers of polyethylene and poly(ethylene glycol), blockcopolymers of poly(dimethyl siloxane) and poly(ethylene glycol) and poly(propylene glycol); said combination having an average molecular weight from about 300 to about 10,000, and wherein the percentage of the ethylene oxide ranges from about 10% to about 95%.
 17. A method according to claim 1 wherein the co-additive is selected from the group consisting of polycaprolactone derivatives consisting of: polycaprolactone diol, polycaprolactone triol, and polycaprolactone tetraol; said combination having an average molecular weight from about 300 to about 5,000.
 18. A method according to claim 1 wherein the co-additive is selected from the group consisting of polyesters made of aliphatic di-alcohols with 2 to 12 carbons and aliphatic di-carboxylic acids with 2 to 12 carbons, said co-additive being selected from one of the following: poly(ethylene azelate), poly(ethylene succinate), poly(1,3-propylene adipate), poly(1,4-butyl adipate), poly[di(ethylene glycol) adipate]; said co-additive having a molecular weight from about 300 to about 5,000.
 19. A method according to claim 1 wherein the co-additive is selected from the group consisting of polyethyleneimine and polycarbonates derivatives, said co-additive being selected from: poly(polytetrahydrofuran carbonate) diol and poly(hexamethylene carbonate) diol; said combination having an average molecular weight of all compounds ranging from about 300 to about 5,000.
 20. A method according to claim 1 wherein the co-additive is selected from the group consisting of compounds represented by formula below:

wherein R₁, R₂, R₃, R₄, and R₅ are same or different alkyl groups, and the anion A is selected from the group consisting of: chloride, bromide, tetrafluoroborate, and methosulfates.
 21. A method according to claim 1 wherein the processing method step (d) comprises a technique selected from the following: injection molding, extrusion blow molding, thermoforming, injection stretching blow molding, film casting, and film blowing.
 22. A method according to claim 1 wherein the co-additive reduces the critical concentration of the diacetal based clarifier by more than 20%.
 23. A method according to claim 1 wherein the co-additive reduces the critical concentration of the diacetal based clarifiers by more than 30%.
 24. A method according to claim 1 wherein the co-additive reduces the critical concentration of the diacetal based clarifiers by more than 40%.
 25. A composition comprising: (a) at least one diacetal represented by formula (II)

wherein R₁, R₂, R₃, R₄, R₅, R₆, R₇, R₈, R₉, R₁₀ are the same or different and each represents one of the following: a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an alkoxycarbonyl group having 1 to 4 carbons, a halogen atom, an hydroxy group, an alkylthio group having 1 to 6 atoms, an alkylsulfoxy group having 1 to 6 carbon atoms, or a 4 or 5 membered alkyl group forming a carbocyclic ring with adjacent carbon atoms of the unsaturated parent ring; n represents 0 or 1; (b) at least one co-additive selected from the group consisting of: block copolymers containing at least one block of poly(ethylene glycol, polycaprolactone derivatives and their copolymers, poly(styrene-co-allyl alcohol), polyesters based on aliphatic di-alcohols and aliphatic di-carboxylic acids and copolymers of such polyesters, polycarbonate derivatives and their copolymers, polyethyleneimine, and imidazole-based ionic liquids; wherein said co-additive provides an average molecular weight above about
 300. 26. An article of manufacture comprising the composition of claim
 25. 27. A composition according to claim 25 wherein the co-additive comprises at least one block copolymer selected from the group consisting of: (1) groups having at least one block of poly(ethylene glycol), and (2) groups having at least one block of polyethylene, polypropylene, polystyrene, or poly(dimethylsiloxane); wherein said composition provides a co-additive average molecular weight between about 300 and about 10,000.
 28. A composition according to claim 25 wherein the co-additive comprises at least one member selected from the group consisting of: poly(styrene-co-allyl alcohol), polyethyleneimine, polycaprolactone diol, polycaprolactone triol, polycaprolactone tetraol; wherein the average molecular weight of said co-additive ranges from about 300 to about 5,000.
 29. A composition according to claim 25 wherein the co-additive comprises at least one member selected from the group consisting of: polyesters made of aliphatic di-alcohols with 2 to 12 carbons and aliphatic di-carboxylic acids with 2 to 12 carbons; wherein the average molecular weight of the co-additive ranges from about 300 to about 5,000.
 30. A composition according to claim 25 wherein the co-additive is selected at least one member from the group consisting of: polycarbonate derivatives, poly(tetrahydrofuran carbonate) diol and poly(hexamethylene carbonate) diol; wherein the average molecular weight of said co-additive ranges from about 300 to about 5,000.
 31. A composition according to claim 25 wherein the co-additive comprises at least one member selected from the group represented by the formula as follows:

where R₁, R₂, R₃, R₄, and R₅ are same or different alkyl groups, and the anion A is selected from the group consisting of: chloride, bromide, tetrafluoroborate, and methosulfate.
 32. A composition comprising (a) at least one diacetals represented by formula (I)

where R is selected from the group consisting of: alkenyls, alkyls, alkoxys, hydroxyl alkyls, and haloalkyls, and derivatives thereof; R₁, R₂, R₃, R₄, R₅, R₆, R₇, R₈, R₉, R₁₀ are the same or different and each may be selected from one of the following: a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an alkoxycarbonyl group having 1 to 4 carbons, a halogen atom, an hydroxy group, an alkylthio group having 1 to 6 atoms, an alkylsulfoxy group having 1 to 6 carbon atoms, or a 4 or 5 membered alkyl group forming a carbocyclic ring with adjacent carbon atoms of the unsaturated parent ring; n represents 0 or 1; (b) at least one co-additive selected from the group consisting of poly(ethylene glycol), poly(ethylene glycol) derivatives, copolymers containing segments of ethylene oxide, polyalcohols and their derivatives, blockcopolymers containing at least one block of a polyalcohol, polycaprolactone derivatives and their copolymers, polyesters based on aliphatic di-alcohols and aliphatic di-carboxylic acids as well as copolymers of these polyesters, polycarbonate derivatives and their copolymers, polyethyleneimine, and ionic liquids; wherein said co-additive provides an average molecular weight of about 300 or greater.
 33. A composition according to claim 32 wherein the co-additive is additionally selected from the group consisting of: poly(ethylene glycol), poly(ethylene glycol) alkyl ether, poly(ethylene glycol) alkyl ester, copolymers containing segments of ethylene oxide, poly(styrene-co-allyl alcohol), polycaprolactone diol, polycaprolactone triol, polycaprolactone tetraol, poly(ethylene azelate), poly(ethylene succinate), poly(1,3-propylene adipate), poly(1,4-butyl adipate), poly[di(ethylene glycol) adipate], polyethyleneimine, 1-ethyl-3-methylmidazolium chloride, 1-hexyl-3-methylimidazolium chloride; further wherein the average molecular weight of said co-additive ranges from about 300 to about 10,000.
 34. A composition comprising (a) at least one polyolefin resin, (b) at least one diacetal-based clarifier provided in said composition at a concentration of about 0.2 parts by weight or less, in relation to 100 parts by weight of the polyolefin resin; and (c) at least one co-additive selected from the group consisting of: poly(ethylene glycol), poly(ethylene glycol) derivatives, copolymers containing segments of ethylene oxide, polyalcohols and their derivatives, blockcopolymers containing at least one block of a polyalcohol, polycaprolactone derivatives and their copolymers, polyesters based on aliphatic di-alcohols and aliphatic di-carboxylic acids and copolymers of these polyesters, polycarbonates derivatives and their copolymers, polyethyleneimine, and ionic liquids; (d) wherein said co-additive provides an the average molecular weight of about 300 or more; and further wherein; and (e) the use level of said co-additive is about 0.05 parts by weight or less, in relation to 100 parts by weight of the polyolefin resin.
 35. A composition according to claim 34 wherein the sum of the use levels of the diacetal based clarifier and the co-additive is 0.2 parts by weight or less, in relation to 100 parts by weight of the polyolefin resin.
 36. A composition according to claim 34 wherein the sum of the use levels of the diacetal based clarifier and the co-additive is 0.18 parts by weight or less, in relation to 100 parts by weight of the polyolefin resin.
 37. A composition according to claim 34 wherein the sum of the use levels of the diacetal based clarifier and the co-additive is 0.15 parts by weight or less, in relation to 100 parts by weight of the polyolefin resin.
 38. A composition according to claim 34 wherein the sum of the use levels of the diacetal based clarifier and the co-additive is 0.12 parts by weight or less, in relation to 100 parts by weight of the polyolefin resin.
 39. A composition according to claim 34 wherein the sum of the use levels of the diacetal based clarifier and the co-additive is 0.1 parts by weight or less, in relation to 100 parts by weight of the polyolefin resin.
 40. A composition according to claim 34 wherein the sum of the use levels of the diacetal based clarifier and the co-additive is 0.08 parts by weight or less, in relation to 100 parts by weight of the polyolefin resin.
 41. A composition according to claim 34 wherein the sum of the use levels of the diacetal based clarifier and the co-additive is 0.06 parts by weight or less, in relation to 100 parts by weight of the polyolefin resin.
 42. A composition according to claim 34 wherein the polyolefin resin comprises at least one member selected from the group consisting of: polypropylene random copolymers, polypropylene homopolymers, polypropylene impact copolymers, linear low density polyethylene, low density polyethylene, and high density polyethylene.
 43. A composition according to claim 34 wherein the polyolefin resin comprises at least one member selected from the group consisting of: polypropylene random copolymer and polypropylene homopolymer.
 44. A composition according to claim 34 wherein the diacetal is at least one member selected from the group consisting of dibenzylidene sorbitol, di(p-methylbenzylidene) sorbitol, di(o-methylbenzylidene) sorbitol, di(p-ethylbenzylidene) sorbitol, bis(3,4-dimethylbenzylidene) sorbitol, bis(3,4-dichlorobenzylidene) sorbitol, bis(3,4-diethylbenzylidene) sorbitol, bis(5′,6′,7′,8′-tetrahydro-2-naphthylidene) sorbitol, bis(trimethylbenzylidene) xylitol, and bis(trimethylbenzylidene) sorbitol.
 45. A composition according to claim 34 wherein the diacetal is at least one member selected from the group consisting of di(p-methylbenzylidene) sorbitol and bis(3,4-dimethylbenzylidene) sorbitol.
 46. A composition according to claim 34 wherein the co-additive is selected from the group consisting of poly(ethylene glycol) and the average molecular weight ranges from about 400 to about 10,000,000.
 47. A composition according to claim 34 where in the co-additive is selected from the group consisting of poly(ethylene glycol) and the average molecular weight ranges from 600 to 10,000.
 48. An article of manufacture made from the composition of claim
 34. 49. A composition according to claim 34 wherein the co-additive a poly(ethylene glycol), said composition having an average molecular weight between 300 and about 10,000.
 50. A composition according to claim 34 wherein the co-additive is a copolymer containing segments of ethylene oxide.
 51. A composition according to claim 34 wherein the co-additive is selected from the group consisting of: polycaprolactones, polycaprolactone diol, polycaprolactone triol, and polycaprolactone tetraol; wherein said composition provides an average molecular weight from about 300 to about 10,000.
 52. A composition according to claim 34 wherein the co-additive is selected from the group consisting of polyesters made of aliphatic di-alcohols with 2 to 12 carbons and aliphatic di-carboxylic acids with 2 to 12 carbons.
 53. A composition according to claim 34 wherein the co-additive is selected from the group consisting of: polyethyleneimine, polycarbonates, poly(polytetrahydrofuran carbonate) diol and poly(hexamethylene carbonate) diol.
 54. A composition according to claim 34 wherein the co-additive is selected from the group consisting of compounds represented by formula II.

wherein R1, R2, R3, R4, and R5 are same or different alkyl groups, and the anion A is selected from the following: chloride, bromide, tetrafluoroborate, or methosulfate.
 55. A composition comprising (a) at least one polyolefin resin, (b) at least one diacetal-based clarifier, and (c) at least one co-additive selected from the group consisting of: poly(ethylene glycol), poly(ethylene glycol) derivatives, copolymers containing segments of ethylene oxide, polyalcohols and their derivatives, blockcopolymers containing at least one block of a polyalcohol, polycaprolactone derivatives and their copolymers, polyesters based on aliphatic di-alcohols and aliphatic di-carboxylic acids and copolymers of these polyesters, polycarbonates derivatives and their copolymers, polyethyleneimine, and ionic liquids; wherein said co-additive exhibits an average molecular weight of about 300 or greater.
 56. A composition according to claim 55 wherein the use level of the diacetal based clarifier is between 0.05 and 1 parts by weight, in relation to 100 parts by weight of the polyolefin resin.
 57. A composition according to claim 55 wherein the use level of the co-additive is between 0.001 and 0.2 parts by weight, in relation to 100 parts by weight of the polyolefin resin.
 58. An article of manufacture comprising the composition of claim
 55. 